In Symfony Console version 3.2.4 and earlier, options with required values were validated correctly. For example:

$ ./robo -f examples/ try:opt-required --foo                                              
  [Symfony\Component\Console\Exception\RuntimeException]  
  The "--foo" option requires a value.                    

In Symfony Console version 3.2.5, this validation step is skipped.

I have verified this in multiple Symfony Console applications, which all break in the same way when upgrading to version 3.2.5.

I have also confirmed that commenting out the line $command->setInputBound(true); in Application.php fixes the symptom. Removing this optimization is not the proposed solution; this is just as far as I got in terms of isolation.

Workaround:

• Call $input->bind($command->getDefinition()); in an event subscriber (probably not a great idea)
• Pin Symfony/Console to 3.2.4 in composer.json